Method for securely creating an endorsement certificate in an insecure environment

ABSTRACT

A Method and system for ensuring security-compliant creation and signing of endorsement keys of manufactured trusted platform modules. The endorsement keys are generated for the trusted platform module (TPM). The TPM vendor selects an N-byte secret and stores the N-type secret in the trusted platform module along with the endorsement keys. The secret number cannot be read outside of the trusted platform module. The secret number is also provided to the credential server of the original equipment manufacturer. During the endorsement key (EK) credential process, the trusted platform module generates an endorsement key, which comprises both the public key and a hash of the secret and the public key. The credential server matches the hash within the endorsement key withy a second hash of the received public key (from the endorsement key) and the vendor provided secret. The EK certificate is generated and inserted into the trusted platform module only when a match is confirmed.

RELATED APPLICATION

The present invention is related to the subject matter of the followingcommonly assigned, copending U.S. patent application Ser. No. 10/749,261entitled “Method For Securely Creating An Endorsement CertificateUtilizing Signing Key Pairs” and filed Dec. 31, 2003.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to security features forcomputer systems and in particular to providing security features duringmanufacture and authentication of trusted platform modules (TPMs). Stillmore particularly, the present invention relates to a method and systemfor providing trustworthy endorsement certificates during manufacture ofplatforms using TPMs and the Endorsement Credential of that platform forthat TPM.

2. Description of the Related Art

As the use of computers to conduct day-to-day business communication(information exchange) via computer networks increases, providingreliable/trustworthy encryption capabilities for each computer systemhas become a vital consideration in the manufacturing process for newsystems. Even for computers utilized to carry out personal enterprises,such as Internet-based transactions, system (and network) securityduring these transactions is important.

One conventional method of providing security for information exchangevia computer networks involves the utilization of certificateencryption. Certificate encryption involves the utilization ofpublic-private key cryptography (e.g., asymmetric cryptography). Inorder to provide this method of encryption, some sort of certificationmechanism is required by which a certificate is provided by a trustedsource to verify the trustworthiness of the encryption pair for aparticular computer system. Those skilled in the computer arts arefamiliar with asymmetric cryptography and the implementation ofpublic-private key pairs and associated certificate to carry out secureexchange of information between computer systems.

One major safeguard required during manufacture of computing devicesthat support certificate creation is against breaches in security (orinadequate security) that may result in the use of the private key beingcompromised. Such breaches may result in a fraudulent injection of anattacker's own public key to generate an endorsement certificate for adevice not manufactured with the security safeguards required for atrusted source. An attacker inserts his own key into the process andobtain a certificate made for that key. Also, the endorsementcertificate (digital signature) system is susceptible to fraud if thesystem using the high-value private key of a device is stolen, either byphysical theft of the device containing the private key, or by discoveryof the private key therein and subsequent copying and use in anotherdevice capable of generating endorsement certificates. Most importantly,one must protect the manufacturing environment such that the machinecontaining the high-value certification key can be assured it is onlygenerating credentials or certificates for machines for which it shouldgenerate these credentials.

As will be appreciated, consumer trust is a key component of thissystem, and a manufacturer must ensure that there are no easy breachesto the system so that consumer trust can be maintained. Typically, usersof a computer device are expected to rely upon blind trust in acceptingthat the device used to generate the certificate has not been stolen andin accepting that the device used to generate the certificate hassufficient safeguards to protect its private key from discovery and use.

With the need for reliable implementation of certificate creation withincomputer systems permeating the industry, the trusted platform module(tpm) to implement the specification of the trusted computing platformgroup (tcg). The tpm is a chip that is manufactured to provide theencryption functionality in a trusted device, which is manufactured by atrusted source. The specification of the tcg and tpm are available onthe web at “.org” internet address “trustedcomputinggroup”.

A TPM vendor is required to implement a part that is compliant with theTCG main specification. An OEM of a system that has a TCG complaint partmust go to further steps to create a Platform Credential that, in part,contains information about the Endorsement key in the TPM. The actualcreation time of the Endorsement key is not important, but it isimportant that this key be created if a Platform Credential is to becreated by the OEM. Since the platform is only in a controlledenvironment up until it leaves its manufacturing facility, this is whenthe credential should be created so that the OEM has a level ofassurance that any credential it is signing is indeed for a platformcreated within its secured environment.

The Endorsement key created is a public/private key pair generatedinternally to a TPM. The public portion is the portion that is signed bythe platform manufacturer. The use of this key is further explained inthe TCG main specification. Since the OEM must feel assured that it issigning EK public keys from systems that it created, one may envisionthat a manufacturing facility would have a central machine with ahigh-value key that creates credentials for all machines within thesecure manufacturing facility. However, it is not always feasible tohave localized, high-performance cryptographic devices with high-valuekeys in the same manufacturing environment. Also, there is still noassurance that some attacker has not placed a rogue machine or even justa rogue key request in the facility to be signed.

The manufacturer of the TPM signs a certificate that is physicallyassociated with the TPM. This certificate is tied to the public portionof the endorsement key, and together they confirm that the public key isthe endorsement key of this particular TPM. The certificate generationmechanism is require to show public certification of the keys so theusers can feel confident that the systems are indeed secure. Thus, thereis great value in having the certificate that says that the public keywas generated inside of a TPM.

Previously, manufacturers were able to protect their devicemanufacturing process by manufacturing the devices in OEM owned andoperated manufacturing facilities that were safeguarded against externalattacks. The devices were thus manufactured in a secure environment(i.e., an environment having a sufficient security rating so as not tocompromise the security level of any device manufactured in theenvironment and one from which an endorsement key could be trusted).

Typically, the manufacturing facility and the secure database (server)are not located at the same physical location, and the former isprovided a much less secure environment than the latter. Also, whilesome OEMs own and control the manufacturing plants in these otherlocations, others license out the manufacture of the devices to amanufacturing vendor. These vendors often do not have the same sense ofurgency or financial ability to provide adequate security againstbreaches/attacks in the manufacturing process.

With the globalization of the manufacturing workforce, due to economicand other considerations, many companies are now establishing/utilizingmanufacturing plants in other locations outside of their direct controland trusted security environment (e.g., countries with cheaper labor).While steps are taken to provide security to these plants and limittheir exposure to breaches or attacks, etc. in the manufacturingprocess, it is more likely and certainly not uncommon for securityfeatures of a remote facility to be compromised.

The OEM must protect the key in order to provide a credential for allcustomers by signing the keys. One method of protecting the keygeneration process involves placement of very expensive hardware (i.e.,an credential server) at each remote manufacturing plant. However,obvious problems with this method includes: (1) controlling security ofthe “trusted” sever would become even more difficult when the hardwareis placed in such a remote location; and (2) even if security could beguaranteed, the expense of providing such high-end secure systems foreach manufacturing facility is very impractical (i.e., to expensive toimplement).

Conventional credential servers located within the OEM environment mustbe able to determine/ascertain which keys to sign and which ones not tosign. For example, with 1000 devices in a manufacturing line, thecredential server has to sign the endorsement keys being returned toeach machine. The credential server needs to know each device from whichthe server receives a public key is a device that should be provided anEK certification. With no way to ascertain whether the keys weregenerated within the TPM, the credential server has no way of makingthis confirmation. Providing an endorsement certificate to even one EKnot generated within a TPM of the manufacturer could severely compromisethe trust placed in the OEM by the customers who ultimately utilize thedevices.

Thus, current manufacturing environments at which TPMs request acertificate from a remotely located trusted source are susceptible tosecurity problems. The lack of security or inadequate security provideslittle comfort to the OEM that a certificate should be issued for allrequests without having to consider the possibility that the process hasbeen tampered with or that private keys have been generated outside ofthe TPM. A method and system that provides some additional confirmationthat an authentication certificate is validly issued to an endorsementkey from a key pair generated within a TPM would be a welcomedimprovement to the manufacturing process.

SUMMARY OF THE INVENTION

Disclosed is a method and system for ensuring security-compliantcreation and signing of endorsement keys of TPMs manufactured in asecond party manufacturing facility. The endorsement keys are created asa pair of asymmetric keys with a public key and a private key. Thesekeys are generated by the TPM vendor/manufacturer according to the TCGprotocol. Prior to generating the devices, the TPM manufacturer selectsan N-byte secret and stores the N-byte secret into the TPM. The N-bytesecret is generated for every X machines, where X is a small enoughnumber to discourage an attacker attempting to figure out the secretnumber while the devices are being manufactured an authenticated and Xis large enough to substantially minimize the cost of having to inject anew N-byte secret number every X devices.

With an X value of 1000, for example, each batch of 1000 machines hasthe same secret, and the next batch of 1000 has a different secret. Thesecret is placed inside of the TPM and cannot be read outside of theTPM. Also, the secret is used once by the TPM, is never readable outsidethe TPM, and is destroyed after it is used.

In an alternate embodiment, X is a time factor and represents the numberof devices that can be generated within X time. The time value isselected based on the same two above criteria for the numeric valueselection. Thus, with an X value of 6 hours, assuming 1500 devices aremanufactured every 6 hours, then each of those 1500 devices share thesame secret number while the next 1500 devices share a different secretnumber.

The secret number is also provided to the OEM prior to the manufactureof the devices. During creation of the endorsement key, the TPM returnsthe public endorsement key as well as the necessary request digest. Thisdigest is a one-way hash of the public endorsement key and the N-bytesecret known only to the TPM and the OEM. The N-byte secret is destroyedonce the hash value of the endorsement key is generated. This preventsan attacker from being able to crack the number. If the TPM is using oneof the secrets previously provided to the credential server, thecredential server matches the hash within the endorsement key with asecond hash of the received public key (from the endorsement key) withthe known secret number. Once a match is confirmed, the credentialserver generates the certificate. In one embodiment, the ability of aTPM to utilize a hash value containing the secret number is valid for apre-established time and expires after a passage of that time.

The above as well as additional objects, features, and advantages of thepresent invention will become apparent in the following detailed writtendescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself however, as well as apreferred mode of use, further objects and advantages thereof, will bestbe understood by reference to the following detailed description of anillustrative embodiment when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a system diagram depicting a TPM manufacturing plant, customerdevice, and central certificate server, which collectively provide theenvironment within which the certificate authentication process of thepresent invention is completed;

FIG. 2 is a block diagram of a customer computer system with a TPM chipaccording to one embodiment of the invention;

FIG. 3 is a block diagram of an exemplary TPM platform within whichvarious implementation steps of the invention are practiced, accordingto one embodiment of the invention;

FIG. 4 is a flow chart illustrating the method of providing certificateendorsement for a TPM's endorsement key using hashed secret numbers inaccordance with one embodiment of the invention;

FIG. 5 is a flow chart illustrating a customer push of the certificationprocess according to one implementation of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENT(S)

The present invention provides a method and system for verifying that anendorsement key was generated within a TPM before creating anendorsement certificate for the TPM device. The invention eliminates theproblems inherent when TPMs are being manufactured in environments thatare susceptible to attacks. The invention is described from theperspective of a remote manufacturing environment (i.e., one that isgeographically remote from the OEM's credential server). However, thefeatures of the invention may be applicable to all manufacturingenvironments including those local to the credential server (i.e., onethat is owned and controlled by the OEM). The TPMs are manufactured withstandard private-public key pairs that require endorsement certificatesfrom a trusted source (per TCG specification, which has been previouslyincorporated by reference.)

The invention describes a credential server of the OEM as the trustedsource. Implementation of the invention requires some hardware/softwareoverhead in both the TPM and the credential server, as well as someadditions to the manufacturing process. As described, thehardware/software overhead includes a register comprised of a selectednumber of bits and, in one embodiment, logic for hashing the valuewithin the register with the public key of the key pair.

The invention is best understood with reference to the various figuresof which FIG. 1 provides a general overview of the manufacturing andauthentication environments (or systems), within which the features ofthe invention are implemented. As provided by FIG. 1, remotemanufacturing plant 103 includes a computer 104, which is utilizedduring the manufacturing process to complete several controllable(programmable) processes, such as injecting a selected/generatedendorsement key pair and secret number (hereinafter “secret”) into theTPMs. Manufacturing plant 103 manufactures customer devices (orplatforms) 101 that include a TPM chip created for an original equipmentmanufacturer (OEM). The OEM environment 108 includes a credential server107 with a high security value. Credential server 107 comprises ahigh-end processing component and affiliated database 106, within whichis stored a record of issued endorsement certificates and secretsreceived from the manufacturing plant's computer 104 (or personnel) viasome secure transfer.

Remote manufacturing plant 103 is communicatively connected tocredential server 107 via network 105, which may be a WAN or LANdepending on the remoteness of the remote manufacturing plant 103 fromthe OEM environment 108 and the level of network security desired.Network 105 may be utilized to pass secure information between remotemanufacturing plant 103 and credential server 107. As will be describedin greater details below, customer device 101 comprises a TPM 150 whichissues an endorsement key request 110 for an endorsement certificate tocredential server 107 and, in return, receives an endorsementcertificate 112 from credential server 107 during the authenticationprocess.

Both credential server 107 (within OEM environment 108) and remotemanufacturing plant 103 have some level of security, indicated bysecurity columns to the right of each block. Credential server 107 ismaintained with maximum security, while remote manufacturing plant 103has some security value between minimum and maximum security levels. Theinvention assumes that the level of security at credential server 107 isnecessarily at a highest level, while that of remote plant is notnecessarily so. The invention operates within that overall systemenvironment to allow a less than completely secure manufacturingfacility to still be provided endorsement certificates for themanufactured TPM key pairs.

FIG. 2 illustrates an exemplary customer device or platform, whichrepresents any one of a number of different devices that may comprise aTrusted Platform Module (TPM), designed according to the TrustedComputing Group (TCG) protocols. Specifically, device 101 comprises aprocessor 210, a memory controller 220, a system memory 230, aninput/output (I/O) controller 240, and an integrated circuit (IC) device(i.e., TPM) 150.

The I/O controller 240 performs I/O functions and supportscommunications with the TPM 150 via link 160. Also, the I/O controller240 supports communications with components coupled to other links suchas a Peripheral Component Interconnect (PCI) bus, an Industry StandardArchitecture (ISA) bus, a Universal Serial Bus (USB), a Firmware Hubbus, or any other bus configured with a different architecture thanthose briefly mentioned. I/O controller 240 may provide the connectionmeans for linking computer system to network and ultimately tocredential server.

FIG. 3 provides an exemplary embodiment of the TPM 150 of FIGS. 1 and 2.TPM 150 comprises one or more integrated circuits placed within aprotective package. As further shown in FIG. 3, TPM 150 comprises aninput/output (I/O) interface 310, a processor 320, internal memory 330(e.g., volatile and/or non-volatile), an asymmetric key generation unit340 and a cryptographic engine 350. Depending on implementation, thecryptographic engine 350 may be part of the processor 320 or separatelogic/component.

The asymmetric key generation unit 340 is configured to create one (ormore) asymmetric key pairs, which includes an asymmetric private key 361and a corresponding asymmetric public key 362. Each asymmetric key pairis used for encryption and decryption operations during a singlecommunication session with another platform and may be erased aftercompletion of the communication session either automatically or throughissuance of an authenticated software command. The generated keys arestored within memory 330. Also provided and stored within memory 330 isa secret 363, which, as is further described below, enables a secondarysecurity check by which the EK certificate may be provided withknowledge that the TPM private key 361 was generated within the TPM 150.At some stage of the authentication process, the endorsement keycertificate may also be stored within the memory 330 of TPM 150.

TPM 150 allows access to certain entities stored in a portion of theinternal memory 330 and/or performance of selected operations by itsplatform only upon receipt of authorization data (e.g., endorsementcertificate) by the processor 320. In order to protect theconfidentiality of an authorization secret (and endorsement certificate)during transmission to the TPM 150 as well as insure the integrity ofthe endorsement certificate, the TPM 150 utilizes a secure datatransmission mechanism. The confidentiality of transmissions isprotected through encryption of the endorsement certificate. Likewise,the certificate's integrity is protected by the ability of thecredential server to verify that the endorsement certificate is beingtransferred to a TPM and that only a specific TPM can decrypt the data.

FIG. 4 illustrates a flow chart of the process completed in a firstimplementation of the invention. It is understood that the various stepsare illustrated in a particular order simply for the present embodimentand other variations in the order of process steps (and processes withadditional or fewer steps covering the same general concepts) fallwithin the scope of the invention. At step 401 of the process, themanufacturer (TPM vendor) builds the TPM chip.

Prior to or concurrent with generating the devices, a TPM vendorgenerates an N-byte secret number that is periodically changed, as isprovided by step 403. The value of N is a parameter that is selectedbased on one or more of the following: (1) cost of implementation; (2)difficulty to crack by brute force attacks; (3) length of time duringwhich the secret number is valid; and other factors. For illustrativepurposes, N is assumed to be 20. The size of the register that has to beincluded within the TPM to hold this secret is proportional to the sizeof the secret, as is the amount of storage space required in thecredential server's database. Also, the method of injecting the secretnumber into the TPM, and the amount of logic required to complete thehashing function (described below) are also determined by the value ofN.

A period, X, is identified for changing the secret number. X may becalculated based on a number of chips manufactured (e.g., every 1000chips), or based on a passage of time (e.g., every 5 days), or someother basis selected by the manufacturer (or the OEM). The N-byte secretis generated for every X machines, where X is a small enough number todiscourage an attacker attempting to figure out the secret number whilethe devices are being manufactured an authenticated and X is largeenough to substantially minimize the cost of having to inject a newN-byte secret number every X devices. With an X value of 1000, forexample, each batch of 1000 machines has the same secret number, and thenext batch of 100 has a different secret number.

In an alternate embodiment, X is a time factor and represents the numberof devices that can be generated within X time. The time value isselected based on the same two above criteria for the numeric valueselection. Thus, with an X value of 6 hours, assuming 1500 devices aremanufactured every 6 hours, then each of those 1500 devices share thesame secret number while the next 1500 devices share a different secretnumber.

Once the secret is generated, the TPM vendor provides the 20-byte numberto the OEM, at step 405. This transfer occurs in a secure exchange andat the time the number is generated, which may be some time before thesecret is actually used. The OEM's credential server records the secretnumber for later use during an endorsement key credential process.

The public/private endorsement key pair is generated and stored in theTPM, as indicated at step 406. The vendor also injects the secret intothe TPM as shown at block 407. The manufactured TPM chip thus comprisesthe public/private key pair and the secret stored in memory. As withstandard key pairs, the public key is available for public display andis transmitted across the network during authentication. The private keyis internal to the TPM and not accessible once generated. The secret isalso not accessible outside of the TPM. According to the presentembodiment, the secret is a single-use-only number. Thus, once utilizedduring the credential process, described below, the secret isdestroyed/deleted.

After the TPM (chip and/or platform) has been fabricated, the credentialprocess is initiated. The TPM chip is installed in the computer systemat step 409 and provided a secure connection to the credential server.Then, at step 411, the TPM generates a public endorsement key (EK)utilized within the credential process. The generation of the EK mayoccur at/during manufacture of the TPM or at some later time in anenvironment in which the private key is protected (not revealed).According to the present embodiment, during creation of the endorsementkey, the TPM returns the public endorsement key as well as the necessaryrequest digest. In the present embodiment, the digest is a one-way hashof the public endorsement key and the N-byte secret known only to theTPM and the OEM. The combination of these values is hereinafter referredto collectively as the endorsement key (EK).

The N-byte secret is destroyed once the hash value of the endorsementkey is generated as shown at step 413. This prevents unauthorized use ofthe number in a security attack on the TPM. Also, this necessitates abrute force attack of the secret number to be carried out acrossmultiple TPMs, making it very unlikely for such an attack to besuccessful. Potential attackers are thus prevented from being able tocrack the secret number.

Following generation of the EK, the EK (PuK and hashed value) isforwarded to the credential server of the OEM at step 415. As previouslydescribed, this credential server is located within a high-valuesecurity environment that is validated by the OEM.

In one embodiment, the credential server is an on-site, highlyprotected, FIPS-4, RSA engine (e.g., 4758 processor), which provideshigh-performance, very secure crypto processing. The RSA engine alsoknows the 20-byte secret number and any necessary revocation data aboutthe shared secret numbers. FIPS (or Federal Information ProcessingStandards) is known in the art and the specification may be found atInternet site “csrc.nist.gov/publications/fips”.

At the credential server, an expected hash value is calculated using thesecret provided beforehand by the TPM vendor and the public key portionof the EK, as depicted at step 416. A comparison is made of the EK hashvalue against the calculated hash, and this comparison leads to adetermination at step 417 whether the EK's hash value matches theexpected/calculated hash value. If the values do not match, then thepublic key cannot be authenticated as coming from a secure TPM and afailure to authenticate is signaled to the customer device as shown atblock 423. This failure is also recorded along with identifying data ofthe customer device and the TPM vendor. This information is recorded ina “failed credential” database associated with the credential server andmay be utilized to track attempts to crack the system from a particularmanufacturing site (or TPM vendor).

When the EK is confirmed as originating from a secure TPM, an EKcertificate is generated by the crypto engine of the credential serverand sent back to the TPM, as shown at step 419. The EK certificate isthen inserted into the TPM at step 421 to enable future authenticationprocesses to be completed/authenticated. The endorsement certificate ispublic readable but once writeable, so that the device only needs to becertified once.

FIG. 5 is a flow chart illustrating a second possible implementation ofthe invention (or simply a second embodiment for the previousimplementation). As in the previous embodiment, the public key and thehashed value are sent to the OEM. The credential server receives the EKat step 501 and generates the EK certificate (following confirmation bythe credential process) and stores the EK in a server database, asdepicted at step 503. The customer is required to request thecertificate from the OEM for this TPM at some later time.

The credential server monitors for a receipt of a request from thecustomer computer for the EK certificate and, at step 504, adetermination is whether the customer has made a request for the EKcertificate. When the customer has made a request for the EKcertificate, the credential server forwards the EK certificate to thecustomer's TPM, as shown at step 505. Notably, in another embodiment,the public endorsement key serves as a trigger that is sent by thecustomer at a later request time to initiate the credential process,which generates the certificate and immediately forwards the generatedcertificate to the requesting customer. The EK certificate is insertedwithin the TPM as indicated at step 507, and encryption functionality ofthe device is enabled. Only an approved EK certificate, based on one ofthe above credential processes on a specific customer device, isprovided in response to a request from that specific customer. As isindicated at step 509, the TPM is not enabled with secure encryptionfunctionality until the customer has requested and received the EKcertificate.

By completing one of the two embodiments described above, a TPMmanufactured at a remote location may be authenticated and provided anEK certificate from the trusted OEM. Both the OEM and users of thedevice are able to trust the validity of manufacturing and credentialprocess and resulting EK certificate and private key irrespective of thelocation at which the device was manufactured.

It is important to note that while the present invention has beendescribed in the context of a fully functional data processing system,those skilled in the art will appreciate that the mechanism of thepresent invention is capable of being distributed in the form of acomputer readable medium of instructions in a variety of forms, and thatthe present invention applies equally, regardless of the particular typeof signal bearing media utilized to actually carry out the distribution.Examples of computer readable media include: nonvolatile, hard-codedtype media such as Read Only Memories (ROMs) or Electrically ErasableProgrammable Read Only Memories (EEPROMs), recordable type media such asfloppy disks, hard disk drives and CD-ROMs, and transmission type mediasuch as digital and analog communication links.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

1. A method for securely creating an endorsement certificate for adevice in an insecure environment, said method comprising: generatingfor a valid device an endorsement key pair that includes a private keyand a public key, wherein said private key is not public readable;creating a non-public, secure value that is provided to both a pluralityof valid devices and a credential server, wherein the value is a firstvalue that is provided to a first set of said plurality of valid devicesand a second set of said plurality of valid devices are provided asecond value, based on a pre-defined method for determining when tochange said first value to said second value from among: a passage of apre-set amount of device manufacturing time and a preset number ofmanufactured devices from among the plurality of valid devices, whereinsaid non-public, secure value is a secret number; transmitting a firstcopy of said secret number via a secure communication medium to saidcredential server; hashing a second copy of said secret number with apublic key from said endorsement key pair; combining a first hash resultfrom said hashing step with the public key to create an endorsement key(EK); transmitting said credential server to initiate a credentialprocess; verifying by utilizing said non-public, secure value that anendorsement key of said valid device is a valid endorsement key of saidendorsement key pair that was generated during manufacture of said validdevice, wherein a function of a first copy of said non-public, securevalue within said credential server matches a similar function of asecond copy of said non-public, secure value associated with theendorsement key received at the credential server, said verifying stepfurther comprising: receiving said EK from said device at the credentialserver, calculating an expected hash value by hashing the public keywithin the received EK with the first copy of said secret numberreceived during said transmitting step, comparing the first hashed valuefrom within the EK with the expected hash value, and confirming said EKis from a valid device when said comparing step results in a match; andin response to confirming said EK is from a valid device, inserting anendorsement certificate into said device to indicate that said device isan approved device by an original equipment manufacturer (OEM) of thedevice.
 2. The method of claim 1, wherein following said verifying stepsaid method further comprises: initially storing the credential in adatabase of said credential server; monitoring for a request from acustomer to provide said certificate to said device; and following areceipt of said customer request, transmitting said certificate to saiddevice to be inserted within the device.
 3. The method of claim 1,wherein said endorsement certificate is once-writeable public-readableand is utilized for signing said public key during communication fromand to said device.
 4. The method of claim 1, wherein said value isinjected into said device, and said value is a single-use parameter,said method further comprising immediately destroying said value withinsaid device following a creation of said BK.
 5. The method of claim 1,wherein said credential server is remotely located from a vendormanufacturing said device and said method comprises communicating saidvalue from said device to said credential server via a securecommunication medium.
 6. The method of claim 1, wherein said device is atrusted platform module (TPM).